For the last several years, we have been studying the molecular interactions of Concanavalin A (Con A) with model sugar substrates and focusing on Con A itself. This was accomplished primarily by metal ion substitution (Co 2 ion for zinc) and physical measurements: CD, MCD, and fluorescence spectroscopy. With the discovery of a new form of Apo Con A designated Apo, we are currently characterizing this new derivative with respect to sugar binding, metal binding and specificity, on and off rates using stop-flow techniques. With our interest in mitogenesis, we have established a collaboration with D.B. Liwnicz of the Department of Pathology who is culturing C6 glioma cells. We quickly found that like lymphocytes, C6 gliomas show a lectin induced mitogenic effect. During lectin induced mitogenesis in lymphocytes surface membrane fluidity changes have been observed. The local membrane fluidity can be studied using NMR and the general fluidity can be studied by fluorescent polarization using lipophilic probes. We will study the biophysical changes induced by binding of mitogenic lectins to the surface of C6 glioma cells and establish to what degree the changes are affected by the level of astrocytic differentiation.